Desulphurisation of hydrocarbon materials



United States Patent Ofiice 3,284,342 Patented Nov. 8, 1966 3,284,342DESULPHURJISATION F HYDRGCARBGN MATERIALS Wilfred Samuel Nathan,deceased, late of Sunbury-on- Thames, Middlesex, England, by hirley(Gerunds Nathan, Surbiton, Surrey, England, and Gerald Stanley Davis,London, England, personal representatives, and John Frederick Ford,Sunhury-on-Thames, England, assignors to The British Petroleum CompanyLimited, London, England, a British joint-stock corporation No Drawing.Filed Nov. 21, 19M, Ser. No. 154,932 Claims priority, application GreatBritain, Nov. 20, 1960, 40,093/60 10 Claims. (Cl. 208-208) Thisinvention relates to the desulphurisation of hydrocarbon materials, forexample hydrocarbon materials of petroleum origin and in particularpetroleum fractions of high molecular Weight.

In general the presence of sulphur or sulphur-containing compounds ishighly undesirable in petroleum crude oils, distillates and residues.Many of the valuable properties of these materials are seriouslyimpaired by the presence of sulphur compounds which results in adowngrading of their commercial value.

In the past numerous processes have been employed either to eliminateundesirable sulphur compounds or to convert them into more innocuousforms. One type of process involves physical extraction with a liquidsolvent such as sulphuric acid, sulphur dioxide, furfural and the like.Another type of process removes the sulphur compounds by adsorption onsuitable materials, for example activated bauxite, activated charcoal oran activated clay. A further type of process converts objectionableforms of sulphur compounds, such as mercaptans, into less harmful forms,such as disulphides and polysulphides by various chemical treatments,for example plumbite treatments, hypochlorite treatments and copperchloride treatments. The above processes are particularly used for thetreatment of gasoline fractions. With feedstocks of high molecularweight, a large proportion of the material is in the form of moleculescontaining at least one sulphur atom, and, particularly in selectiveseparation processes, this would be removed with consequent low productyield.

Yet another type of process which has been found particularly useful forthe treatment of middle distillate fractions such as gas oils comprisespassing the material, generally with hydrogen under pressure, over asuitable catalyst at elevated temperature in order to eliminate thesulphur atoms from the sulphur-containing compounds in the form ofhydrogen sulphide. It is the object of this type of process to sever thecarbon-sulphur linkages in the sulphul containing compounds, eliminatingthe sulphur in the form of hydrogen sulphide while at the same timehydrogenating the hydrocarbon fragments left as a result of thedesulphurisation reaction.

It has been found, however, that in order to effect appreciablereductions in the sulphur content of high moiecular weight material, forexample residual fuel oils, the conditions required for such hydrogentreatments are severe; and the catalyst life is shortened by depositformation.

According to the present invention a process for the desulphurisation ofsulphur-containing hydrocarbon materials comprises submitting thehydrocarbon material to a selective oxidation reaction in which thesulphur-containing compounds are selectively attacked followed bysubjecting the oxidised material to a thermal decomposition step inwhich the sulphur is eliminated as a sulphurous gas.

The process of the present invention is particularly suitable for thedesulphurisation of petroleum fractions containing at least a proportionof material boiling above 250 C., for example crude oil and atmosphericand vacuum residues, which may contain 1% wt. of sulphur or more.Furthermore it is relatively easy to dispose of sulphurous gases andalso the utility requirements of oxidative and thermal treatments arerelatively low.

A number of oxidising agents may be employed in the selective oxidationstep, for example organic and inorganic peroxides, hydro peroxides,organic and inorganic peracids, chlorine, oxides of ntrogen, ozone,molecular oxygen or air. Owing to its cheapness the preferred oxidisingagent is molecular oxygen or air. The molecular oxygen or air may bepromoted with suitable materials, for example metals from Group SA andGroup 8 of the Periodic Table or their salts or oxides, particularlyplatinum, palladium, nickel and vanadium. These promoters may besupported on a suitable material, for example alumina, soda-lime oractive carbon. Where the supporting material has acidic, and thereforecracking, properties as in the case of alumina, these may be modified bytreatment with an alkali metal, particularly sodium, or an ammoniumcompound. The use of such promoting materials improves the selectiveoxidation and also increases the rate of reaction, allowing the processto be completed in a shorter time or, alternatively, at a lowertemperature.

The preferred reaction conditions required for this oxidation step willdepend both on the material being treated as well as on the oxidisingagent being employed. Preferably, however, a temperature within therange to 180 C. is employed with a quantity of oxidising agentcorresponding to between 1 and 6 active oxygen atoms per atom of sulphurin the feedstock for a period of between /2 and 20 hours. When usingmolecular oxygen or air as oxidizing agent suitable tempenatures liewithin the range to C. for periods of between 2 and 20 hours.

The thermal decomposition step is carried out at temperatures above 200C. preferably above 250 C. and particularly in the range 300-400 C. fora period sufficient to ensure that all the gaseous decomposition products are given oh". This period may be within the range /2 to 5 hourspreferably between /2 and 2 hours. Under these conditions, the oxidisedsulphur compounds are decomposed and the sulphur is liberated mainly asS0 although at higher temperatures in the region of 350 C. and over,increasing quantities of H 8 are also liberated. The thermaldecomposition step may also be carried out in the presence of suitablepromoting materials. Suitable promoting materials comprise porous solidshaving acidic or basic properties for example, ferric oxide on alumina,bauxite, thoria on pumice, silica-alumina, soda-lime and acid sodiumphosphate on carbon. Preferably, in the thermal decomposition step, asmall quantity of an inert carrier gas, for example nitrogen, is passedthrough the reaction mixture to avoid local overheating and also toremove the gaseous decomposition products.

The invention is illustrated by means of the following examples:

EXAMPLE 1 An atmospheric residue derived from a Kuwait crude oil andcontaining 4% weight sulphur was first oxidised with various oxidisingagents and subsequently subjects to a thermal decomposition by rapidlyheating to 370 C. During the thermal decomposition stage a smallquantity of an inert carrier gas (nitrogen) was passed through thematerial to remove the gaseous decomposition products and to preventlocal overheating. For comparison, the thermal decomposition step wasalso carried out on the 0 unoxidised residue. The results are indicatedin the following Table 1:

ing oxidant, the mol ratio of peroxide to the sulphur present being fromabout 1:1 to about 6:1, heating the treated oil containing sulfones at atemperature from TABLE 1 a a about 350 C. to about 400 C. underconditions to Moles Oxidation Sulphur, 5 rupture the sulphur-carbon bondyielding volatile sulphur Oxidising Reagent Reagent/g. Temp era- Time,Percent compounds, and recovering a heavy hydrocarbon 011 Of Atoms Howsreduced sulphur content.

2. A process for the desulphurization of a petroleum None n M fractioncontaining at least a major portion of material (lgmenlegygroperoxiieh 2110 1 3.3 boiling above 250 C. and having a sulphur content of gi g y zifggiz i: Z 23 5: at least 1% by weight, the sulphur :being present insaid n drogex lf roxide/ 6 98 O r 3 5 fraction in the form of sulphurcompounds of high 233 g M 180 7 molecular weight, aid process comprisingcontacting the Barium Per0xide 0.0 90 0.5 3.6 fraction with an oxrdmgagent to selectively oxidize the sulphur-containing compounds of highmolecular weight, said oxidation bein carried out at temperatures withinXA L 2 o a P MP E the range 80-180 C. and for a period of time betweenThe atmospheric res1due of Example 1 was oxidised with /2 and hours, theamount of oxidizing agent employed molecular oxygen both alone and thenin the presence of being equivalent to between 1 and 6 active oxygenatoms various promoters. The oxidised material was then 20 per atom ofsulphur in the fraction; subjecting the oxidized thermally decomposed at370 C. as in Example 1. Reroduct to a thermal decomposition at atemperature in sults are lndrcated 1n the followmg Table 2: the range200400 C. and for a period of time from /2 TABLE 2 Tempcr- AbsorbedSulphur, Oxldising Reagent Modified By ature, Oxygen, Duration, PercentC. Litres/ Hours Weight in 100 g. Product Molecular Oxygen-.- N0 addedAgent 180 2. 1 3. 0 3. 9 Nickel Bromide on Active Carbon 135 2. 7 21 3.2Platinum on Alumina 160 5. 0 0.5 3. 3 Sodium and Platinum on Alumina"200 5. 7 5. 5 3. 5 Ammonium and Platinum on Alumina 180 8.5 11.5 3. 4Palladium on Alum 180 8. 2 6. 0 3. 5 Palladium on Alumin 100 8. 3 13. 53. 5 Vanadium Pentoxide on Alumina... 160 8. 9 5. 0 3. 5 VanadiumPentoxide on Active Carbon 16 4. 5 3. 5 3. 5 Vanadium Pentoxide onSoda-lune 160 6. 2 14. 5 3. 1 Sodium plus Vanadium Pentoxide on Alumina160 8. 5 4. 5 3. 5

EXAMPLE 3 to 5 hours to thermally decompose the oxidized sulphur Theatmospheric residue of Example 1 was oxidised in the presence ofhydrogen peroxide and acetic acid under the following oxidationconditions:

Residue 2 pts by weight. Toluene 1 pt by Weight. Glacial acetic acid 1pt by weight.

Hydrogen peroxide w./v. Quantity corresponding to 6 active oxygen atomsper atom of sulphur.

Temperature 98 C.

Time of reaction 25 minutes.

Time of stripping 25 minutes.

The oxidised residue was then subjected to a thermal decomposition tepat 370 C. as in Example 1, first in the absence of any promoters andthen in the presence of various promoters. Results are indicated in thefollowing Table 3:

TABLE 3 Decomposition promoter: Sulphur Percent weight in product 1. Aprocess for reducing the sulphur content of a sulphur-containing heavyhydrocarbon oil containing at least a proportion of material boilingabove 250 C., which t omprises treating the oil with aperoxide-containcompounds and liberate the sulphur as a sulphurous gas,removing the gaseous decomposition products irom the product of saiddecomposition step, and recovering the desulphurized product.

3. A process in accordance with claim 2 wherein the oxidizing agent isselected from the group consisting of molecular oxygen and air, thetemperature during the oxidation being between 180 C. and for a periodof time between /2and 20 hours.

4. A process as claimed in claim 2 wherein the oxidising agent ispromoted with a material selected from the roup consisting of Group SAand Group 8 metals, their salts and oxides, on a suitable support.

5. A process as claimed in claim 2 wherein the thermal decompositionstep is carried out at a temperature above 250 C.

6. A process as claimed in claim 5 wherein the thermal decompositionstep is carried out at a temperature within the range 300400 C., for aperiod of /2 to 2 hours.

7. A process as claimed in claim 2 wherein the thermal decompositionstep is promoted by porous solid materials having acidic or basicproperties.

8. A process as claimed in claim 7 wherein the thermal decompositionstep is promoted by a material selected from the group comprising ferricoxide on alumina, bauxite, thoria on pumice, ilica alumina, soda-limeand acid sodium phosphate on carbon.

9. A process as olairned in claim 2 wherein a small quantity of an inertcarrier gas is passed through the reaction mixture in the nhermaldecomposition stage.

10. A process as claimed in claim 2 wherein a small quantity of nitrogenis passed through the reaction mixture in the thermal decompositionstage.

(References on following page) 6 References Cited by the Examiner2,414,963 1/1947 McConnell 208-208 UNITED STATES PATENTS 2,955,12310/1960 FaViS 208208 3 3%? 2w; gg DELBERT E. GANTZ, Primary Examiner.

1sc e-r 1/1932 Borgstmm 208 196 5 ALPHONSO D. SULLIVAN, Exammer. 8/1934Benedict 208-208 S. P. JONES, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,284,342 November 8 1966 Wilfred Samuel Nathan, deceased, by ShirleyGertrude Nathan and Gerald Stanley Davis, personal representatives, eta1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

In the heading to the printed specification, line 12,

for "Nov. 20, 1960" read Nov. 22, 1960 column 2, line 10, for "ntrogen"read nitrogen line 65, for "subjects" read subjected Signed and sealedthis 12th day of September 1967.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner ofPatents

1. A PRICESS FOR REDUCING THE SULPHUR CONTENT OF A SULPHURR-CONTAININGHEAVY HYDROCARBON OIL CONTAINING AT LEAST A PROPORTION OF MATERIALBOILING ABOVE 250*C. WHICH COMPRISES TREATING THE OIL WITH APEROXIDE-CONTAINING OXIDANT, THE MOL RATIO OF PEROXIDE TO THE SULPHURPRESENT BEING FROM ABOUT 1:1 TO ABOUT 6:1, HEATING THE TREATED OILCONTAINING SULFONES AT A TEMPERATURE FROM ABOUT 350*C. TO ABOUT 400*C.UNDLER CONDITIONS TO REPTURE THE SULPHUR-CARBON BOND YIELDING VOLATILESULPHUR COMPOUNDS, AND RECOVERING A HEAVY HYDROCARBON OIL OF REDUCEDSULPHUR CONTENT.